In the production of hydrogen, it is well known in the art to treat hydrocarbon material with a catalyst at high temperatures in the presence of steam. Hydrogen, carbon monoxide and carbon dioxide are the products of the reaction. These products are often cooled and passed over a shift conversion catalyst where the carbon monoxide is further reacted with steam to produce additional hydrogen and carbon dioxide.
Generally, the hydrocarbon material which is subjected to such steam reforming processes is first desulfurized. For example, a naphtha is treated with hydrogen in the presence of a hydrodesulfurization catalyst which converts the sulfur in the organic sulfur compounds to hydrogen sulfide. The hydrogen sulfide is then removed from the reformer feedstream by adsorption on zinc oxide. Heavier distillate fuels such as No. 2 fuel oil cannot be adequately desulfurized by hydrodesulfurization and are not considered suitable fuels for steam reforming.
Use of such fuels results in poisoning of the catalyst surface. While steam reforming can still be affected even with the poisoned catalyst, this poisoning does reduce the activity of the catalyst several orders of magnitude. In order to compensate for the reduced activity, steam reformers have been operated at higher temperatures in an attempt to overcome the reduced activity of the catalyst. In addition to requiring greater inputs of energy to maintain the elevated temperatures, the activity of the catalyst is still lower than desired and the use of such elevated temperatures has resulted in rapid decay of the catalyst.
Accordingly, what is needed in this art is a high activity steam reforming catalyst with improved sulfur tolerance.